During rescue hoist operations, helicopter pilots sometimes face the difficult task of maintaining a stabilized hover position in degraded visual conditions. When over water, the task is further complicated by the motion of the waves and the drifting of the victim(s). Maintaining a hover over the victim requires the pilot to constantly adjust the helicopter's position. These adjustments are made based on the verbal instructions given to the pilot by a crewmember.
To aid in making such adjustments, researchers and engineers from the U.S. Army Aeromedical Research Laboratory, Defence Research and Development Canada, and Henry M. Jackson Foundation evaluated the effectiveness of a tactile display system in maintaining and/or improving pilot performance during a hover maneuver over a moving target.
To effectively assess the tactile system in maintaining a stabilized hover, the study used the tactile situation awareness system-Lite belt, and USAARL's one-of-a-kind NUH-60 Black Hawk flight simulator.
The idea of TSAS was to develop a device that provides pilots with information via the sense of touch. Within the last 10 years, engineers from Engineering Acoustics, Inc. manufactured the electromechanical tactors, which produce vibrating pulses that are similar to the vibration of a standard electric toothbrush.
The full TSAS array consists of a custom fit, upper-body torso suit, shoulder straps, and a seat. All three components contain tactors, which transmit information from the flight simulator or aircraft to TSAS and provides, to the pilot, tactile cues such as the aircraft's altitude, position, and velocity. For example, when the helicopter or simulator drifts to the left, the corresponding left position tactor vibrates to alert the pilot of the drift so that he/she can compensate by moving the helicopter to the right. TSAS is designed so that as it alerts the pilot, he/she is able to maintain orientation while looking away from the aircraft's instrument panel.
Over the years, however, the bulky, upper-body torso suit proved unrealistic for operational use. Therefore a smaller and lighter ensemble, the TSAS-Lite belt, became part of the system, which also includes tactors in the shoulder harness and seat cushion. The TSAS-Lite belt, consisting of eight electromechanical tactors, is placed around the waist. The simulator transmits information to the belt, shoulder straps, and seat tactors. The tactors then provide cues to the pilot regarding the aircraft's orientation.
During the two-day study, 16 Black Hawk pilots completed 4 simulated flights per day to a ship where the helicopter landing deck was used as the moving target. In each flight, the participants hovered the helicopter over the moving target for approximately10 minutes. Day one conditioned the aviators to be rested while performing the maneuver, with and without TSAS-Lite, in both a clear (seven miles of visibility) and degraded (overcast, with less than a quarter mile visibility) visual environment. During day two, following one night of continuous wakefulness, the fatigued aviators performed the same maneuver in both visual environments with the presence and absence of TSAS-Lite.
The results showed that the limited-display and use of the TSAS-Lite belt helped increase hover accuracy during low speed hovers in clear and degraded visual conditions, which may increase safety. For example, the participants' performance greatly improved when hovering over the target while using TSAS-Lite. In rested and fatigued pilots, all measures of performance related to aircraft orientation were improved with use of the belt compared to performance without the belt.
Participants rated their situation awareness as greater when the tactile system was active rather than inactive. Participants also rated their perception of target drift relative to their position as better when using TSAS. In addition, pilots perceived workload to be diminished when the tactile system was active thus indicating that the additional information was not a burden or distraction to the pilot.
The findings support the tactile system as an effective device for facilitating performance of this task under varied conditions (rested versus fatigued and clear versus degraded visual environment). Additionally, the data indicate that participants developed a strategy for using the cues, which influenced their performance. Overall, the results show that the belt significantly improved pilot perception of drift and situation awareness, and reduced mental stress.
The information above is a summary of USAARL Technical Report No. 2013-09.